Typically, wind turbines include a rotor having a plurality of wind turbine blades mounted on a hub; a drive train and a generator housed in a nacelle; and a tower. The blades each include an upwind side and a downwind side, each of which is upwind and downwind of the rotor plane. In optimal operation, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket pulls the blade toward it, causing the rotor to turn.
A spinner of a wind turbine represents the outer external shell of the rotating portions of the wind turbine (excluding the blades). The blades themselves have a relatively cylindrical cross-section in the region about the blade that is attached to the hub through the spinner. In known wind turbines, the spinner and the generally cylindrical root region of the blades allow air to easily flow over the spinner and inboard region of the blades contributing near zero aerodynamic advantage to the wind turbine system. Moreover, because of the ease of air flow over the spinner and inboard region of the blades, the axial induction inboard is typically small. This small axial induction results in a region of space along the rotor axis in which air not only flows freely, but also, because of larger induction outboard (larger static pressure), a “speed up” effect occurs. With such a “speed up” effect, air flow bends in toward the spinner and root region of the blades, and also denies flow to outboard regions of the blades where contributions to rotor torque are larger and aerodynamics are more efficient. As a result, current wind turbine structures produce few aerodynamic advantages along the axis of rotation of the rotor, and actually have detrimental effects on inboard aerodynamics for the associated wind turbine.